Provided is an auxiliary burner for an electric furnace capable of increasing and homogenizing the heating effect of iron scrap by suitably and efficiently burning solid fuel along with gas fuel. This auxiliary burner 100 for an electric furnace comprises a solid fuel injection tube 1, a gas fuel injection tube 2, and a combustion-supporting gas injection tube 3 in the stated order from the center side, all arranged coaxially, and is characterized in that: a flow path 30 of the combustion-supporting gas injection tube 3 is provided with a plurality of swirl vanes 4 for swirling the combustion-supporting gas, and a flow path 20 of the gas fuel injection tube 2 is provided with a plurality of swirl vanes 5 for swirling the gas fuel; and the angle .sub.1 of the swirl vanes 4 and the .sub.2 of the swirl vanes 5 satisfy the relationship .sub.1<.sub.2.

Provided is an auxiliary burner for an electric furnace capable of increasing and homogenizing the heating effect of iron scrap by suitably and efficiently burning solid fuel along with gas fuel. This auxiliary burner 100 for an electric furnace comprises a solid fuel injection tube 1, a gas fuel injection tube 2, and a combustion-supporting gas injection tube 3 in the stated order from the center side, all arranged coaxially, and is characterized in that: a flow path 30 of the combustion-supporting gas injection tube 3 is provided with a plurality of swirl vanes 4 for swirling the combustion-supporting gas, and a flow path 20 of the gas fuel injection tube 2 is provided with a plurality of swirl vanes 5 for swirling the gas fuel; and the angle .sub.1 of the swirl vanes 4 and the .sub.2 of the swirl vanes 5 satisfy the relationship .sub.1<.sub.2.

Premixing fuel and oxidizer in a burner to form a flammable mixture is described. The burner is configured to reduce formation of a pollutant when the fuel and the oxidizer are combusted while deterring upstream propagation of the combustion reaction. The burner includes a mixer for premixing fuel and oxidizer to form a flammable mixture to be supplied to a reaction zone for a combustion reaction and a flame arrestor for deterring upstream propagation of the combustion reaction. In some embodiments, the mixer and the flame arrestor include a packing volume. In some embodiments, the mixer and the flame arrestor include at least a first packing volume for containing first packing, a second packing volume for containing second packing, and a packing gap in fluid communication between the first packing volume and the second packing volume.

Premixing fuel and oxidizer in a burner to form a flammable mixture is described. The burner is configured to reduce formation of a pollutant when the fuel and the oxidizer are combusted while deterring upstream propagation of the combustion reaction. The burner includes a mixer for premixing fuel and oxidizer to form a flammable mixture to be supplied to a reaction zone for a combustion reaction and a flame arrestor for deterring upstream propagation of the combustion reaction. In some embodiments, the mixer and the flame arrestor include a packing volume. In some embodiments, the mixer and the flame arrestor include at least a first packing volume for containing first packing, a second packing volume for containing second packing, and a packing gap in fluid communication between the first packing volume and the second packing volume.

A water supplying step of supplying water to a liquid-fuel channel of a nozzle is executed during a liquid fuel supply state in which only liquid fuel is supplied to the nozzle; a post-switch water purging step of supplying water to the liquid-fuel channel of the nozzle is executed during a gas fuel supply state in which only gas fuel is supplied to the nozzle; and a mid-switch water purging step of supplying water to the liquid-fuel channel of the nozzle is executed during a fuel switching state which is a state of transition from the liquid fuel supply state to the liquid fuel supply state. A second flow rate of water supplied in the mid-switch water purging step is lower than a first flow rate of water supplied in the water supplying step. In the post-switch water purging step, water is temporarily supplied at a third flow rate which is higher than the second flow rate.

A water supplying step of supplying water to a liquid-fuel channel of a nozzle is executed during a liquid fuel supply state in which only liquid fuel is supplied to the nozzle; a post-switch water purging step of supplying water to the liquid-fuel channel of the nozzle is executed during a gas fuel supply state in which only gas fuel is supplied to the nozzle; and a mid-switch water purging step of supplying water to the liquid-fuel channel of the nozzle is executed during a fuel switching state which is a state of transition from the liquid fuel supply state to the liquid fuel supply state. A second flow rate of water supplied in the mid-switch water purging step is lower than a first flow rate of water supplied in the water supplying step. In the post-switch water purging step, water is temporarily supplied at a third flow rate which is higher than the second flow rate.

A dual fuel burner system includes a fuel burner housing and a main fuel supply conduit within the fuel burner housing. A main fuel nozzle is positioned proximate to a downstream end of the fuel burner housing and is in fluid communication with the main fuel supply conduit. The main fuel supply conduit is configured to provide 100% of the heat input requirement of the dual fuel burner system. A secondary fuel supply conduit is within the fuel burner housing. The secondary fuel supply conduit is configured to provide 100% of the heat input requirement of the dual fuel burner system. An air circuit is in fluid communication with an outlet of the main fuel nozzle. A direct spark ignitor is positioned proximate to the outlet of the main fuel nozzle.

An arrangement for adjusting the ratio between supplied amounts of fuel (PA) and air (I) in a burner, which is intended for a gaseous and/or liquid fuel is disclosed. The burner comprises a fuel and air mixing zone, a fuel supply conduit adapted to supply the mixing zone with a given inlet flow of fuel, a combustion air supply means adapted to supply the mixing zone with a given inlet flow of combustion air, and burner automation. The burner automation contains measuring instruments. The burner has its mixing zone accompanied by a combustion chamber which is in communication with a flue gas conduit. The combustion chamber or flue gas conduit has at least one catalytic zone. In the arrangement, the measuring instruments include at least one sensor, such as a lambda sensor, measuring the amount of residual oxygen in flue gases (flue gas oxidation/reduction potential). In the arrangement adjustment for an inlet flow (Q.sub.I, Q.sub.Itot) of combustion air generated by the combustion air (I) supply means (determined as a volume flow per unit time), as well as the adjustment for an inlet flow (Q.sub.PA, Q.sub.PAtot) of fuel arriving in the mixing zone by way of the fuel supply conduit (determined as a volume flow per unit time), by means of burner automation, is based on the amount of residual oxygen measured from flue gases (S) with the measuring instrument, by way of which the burner automation adjusts the relative ratio between said inlet flow (Q.sub.I, Q.sub.Itot) of combustion air as well as the inlet flow (Q.sub.PA, Q.sub.PAtot) of fuel in such a way that the amount of residual oxygen is within the range of 0.05-0.5% in flue gases prior to the catalytic zone.

A heater assembly can be used with a gas appliance. The gas appliance can be a dual fuel appliance for use with one of a first fuel type or a second fuel type different than the first. The heater assembly can include a pressure sensor and a plurality of valves operable by a control module dependent upon a detected fuel pressure. The valves may be solenoid valves that can reduce the available fuel delivery paths to limit fuel delivery to a burner when a higher pressure, such as detection of LP gas, is detected.

An apparatus for producing a stabilizing base flame for a premix main burner flame in a burner assembly having a burner end, a first fuel line, a first fuel nozzle, a second fuel line, and a second fuel nozzle. The apparatus comprises a conduit having a first fuel line end in fluid communication with the first fuel line, a second fuel line end in fluid communication with the second fuel line, a valve in fluid communication with the conduit and a center fuel stabilization bluff body mounted in the burner end. The center fuel stabilization bluff body comprises a first ring, a second ring and a cylinder disposed between the first ring and the second ring.